var n,i,nr,tot:longint;
    f,g:text;

function prim(x:longint):boolean;
var l:longint;
    begin
    for l:=2 to trunc(sqrt(x)) do
        if x mod l=0 then
           begin
           prim:=false;
           exit;
           end;
    end;

begin
assign(f,'fractii.in');reset(f);
assign(g,'fractii.out');rewrite(g);
readln(f,n);
tot:=0;
for i:=2 to n do
    if prim(i) then
       begin
       tot:=tot+n-n div i;
       nr:=nr+1;
       end;
tot:=tot*2;
tot:=tot-(nr*nr-nr)+n-nr+1;
writeln(tot);
end.